CN115536620A

CN115536620A - System and method for continuously producing furfural and 5-hydroxymethyl furfural by cellulose biomass

Info

Publication number: CN115536620A
Application number: CN202211242346.3A
Authority: CN
Inventors: 陈玮; 陈志勇; 常春
Original assignee: Hongye Holding Group Co ltd; Henan Bio Based Materials Industry Research Institute Co ltd
Current assignee: Hongye Holding Group Co ltd; Henan Bio Based Materials Industry Research Institute Co ltd
Priority date: 2022-10-11
Filing date: 2022-10-11
Publication date: 2022-12-30
Anticipated expiration: 2042-10-11
Also published as: CN115536620B

Abstract

The invention provides a system and a method for continuously producing furfural and 5-hydroxymethylfurfural from cellulose biomass. The system and the method provided by the invention take cellulose biomass as a raw material to continuously prepare furfural and 5-hydroxyfurfural, and the continuous hydrolysis system is used for preparing furfural and 5-hydroxyfurfural, wherein the hemicellulose component is converted into furfural, the cellulose component is converted into 5-hydroxymethylfurfural, lignin can be byproduct, and the utilization rate of the raw material component is improved to the maximum extent; meanwhile, the method has the characteristics of low energy consumption and less three-waste discharge, the whole hydrolysis process is continuous, and cellulose biomass can be continuously and synchronously used for preparing furfural and 5-hydroxymethylfurfural high-value chemicals.

Description

System and method for continuously producing furfural and 5-hydroxymethyl furfural by cellulose biomass

Technical Field

The invention belongs to the field of comprehensive utilization of agricultural and forestry residues, and particularly relates to a system and a method for continuously producing furfural and 5-hydroxymethylfurfural from cellulose biomass.

Background

With the increasing consumption of non-renewable fossil resources, the production of high-value chemicals from renewable cellulosic biomass has become one of the important directions for sustainable development in the chemical industry. Cellulose biomass is abundant and widely available, and its main chemical components are hemicellulose, cellulose and lignin. Cellulosic biomass components can be converted to a wide variety of high-value chemicals by different conversion techniques.

Furfural is a bulk chemical prepared by hydrolysis of cellulose biomass, and can be widely used in the fields of medicines, pesticides, plastics, petrochemicals and the like. The preparation principle is that the hemicellulose component of cellulose biomass is firstly hydrolyzed into pentose, and then is further dehydrated to generate furfural. At present, the raw materials of furfural industrial production mainly comprise corncobs and bagasse, sulfuric acid or hydrochloric acid is mainly used as a catalyst, xylan in biomass is converted into furfural at high temperature and high pressure, and the generated furfural is removed in time by continuously introducing steam. And condensing and layering a mixture containing furfural and water vapor, introducing an oil phase (furfural) into a stripping tower, condensing the distillate at the top of the tower, and further refining and purifying to obtain a furfural finished product. The production process has the advantages of single technical route, low conversion utilization rate of raw materials and less high-value products. And a large amount of acid-containing waste liquid and solid residues are generated in the furfural production process, the recycling difficulty is high, the cost is high, and the environment is damaged.

5-hydroxymethylfurfural is another platform chemical which can be prepared by hydrolyzing cellulose biomass, and has great application prospect in the fields of liquid fuels, high polymer materials, pharmacy and chemical products due to excellent chemical properties. The 5-hydroxymethylfurfural can be obtained by hydrolyzing cellulose components of a cellulose biomass raw material, hydrolyzing the cellulose into hexose, and dehydrating to obtain the 5-hydroxymethylfurfural. However, the production of 5-hydroxymethylfurfural also adopts a preparation process route of a single product at present, and the economical efficiency of the conversion process is poor.

In order to overcome the defects of the prior art, the invention aims to provide a system and a method for continuously producing furfural and 5-hydroxymethylfurfural by cellulose biomass, so as to improve the utilization rate of raw materials, fully utilize hemicellulose, cellulose and lignin in the raw materials and realize the complete conversion of the raw materials while solving the problems of high production cost of furfural and pollutant discharge; meanwhile, the waste liquid is recycled to prevent environmental pollution.

Disclosure of Invention

The invention aims to provide a method and a system for continuously preparing furfural and 5-hydroxymethylfurfural from cellulose biomass, which can realize the complete utilization of cellulose and hemicellulose components of the cellulose biomass, simultaneously obtain furfural and 5-hydroxymethylfurfural high-value chemicals in a continuous conversion process, and can produce a byproduct of lignin.

In a first aspect of the invention, the invention provides a method for continuously preparing furfural and 5-hydroxymethylfurfural from cellulosic biomass, comprising:

a. after crushing the cellulose biomass raw material, mixing the crushed material with an acid catalyst, and then adding the mixture into a furfural continuous hydrolysis kettle;

b. the raw materials fall into the hydrolysis kettle from the upper part of the hydrolysis kettle in a gravity mode, steam is introduced into the bottom of the hydrolysis kettle, continuously generated furfural-containing steam is discharged from the top of the hydrolysis kettle, and furfural is obtained after cooling; discharging furfural residues after reaction from the bottom of the hydrolysis kettle;

c. mixing the discharged furfural residues with a catalyst solution, pumping the mixture and an organic solvent into a 5-hydroxymethylfurfural continuous hydrolysis reactor at the same time, introducing steam into the bottom of the reactor, and feeding the effluent reaction liquid into a separation system;

d. and (3) carrying out solid-liquid separation on the effluent reaction liquid through a solid-liquid separator, carrying out phase separation on the separated liquid phase to obtain an organic phase and a water phase, and recovering the solvent from the organic phase to obtain the 5-hydroxymethylfurfural.

In a preferred embodiment, the cellulosic biomass feedstock is mixed with the acid catalyst by means of an acid-mixing screw feeder.

In a preferred embodiment, the mixed raw material of the cellulose biomass raw material and the acid catalyst is fed into the furfural continuous hydrolysis kettle through a channel of a feeding device connected with the furfural continuous hydrolysis kettle, and the feeding device can be a continuous screw pressure feeding device. Preferably, the feeding device forms a material plug at a discharge hole to compress the material, and the compressed material enters the furfural continuous hydrolysis kettle through a material stirring blowout preventer at a feed hole at the top of the furfural continuous hydrolysis kettle.

In a preferred embodiment, the furfural-containing steam is subjected to heat exchange by a cooler and then enters an extraction unit for refining.

In a preferred embodiment, the reacted furfural residue is discharged through an automatic residue discharge device arranged at the bottom of the hydrolysis kettle and enters a screw conveyor, and the catalyst solution is continuously added from a catalyst solution tank in the continuous furfural residue conveying process.

In a preferred embodiment, the reaction liquid flowing out of the continuous hydrolysis reactor for 5-hydroxymethylfurfural is cooled by a cooler and then subjected to solid-liquid separation in a solid-liquid separator.

In the invention, the separated solid slag mainly comprises lignin after being dried, and can be used as boiler fuel.

In one embodiment, the aqueous phase resulting from the phase separation is subjected to organic solvent extraction to further recover 5-hydroxymethylfurfural.

Preferably, the aqueous phase obtained by phase separation is extracted by an organic solvent and separated to obtain an organic phase and an aqueous phase, and the organic phase is subjected to solvent recovery to obtain 5-hydroxymethylfurfural; the aqueous phase can be recycled for use as feed water.

Preferably, the phase separation according to the invention is carried out in a phase separator.

In one embodiment, the 5-hydroxymethylfurfural obtained after recovery of the solvent may be fed to a refining unit for refining.

Therefore, in one embodiment, the reaction liquid flowing out of the continuous 5-hydroxymethylfurfural hydrolysis reactor enters a primary separation system, the reaction liquid is cooled by a cooler and is subjected to solid-liquid separation by a solid-liquid separator, the separated solid slag can be used as boiler fuel after being dried, the separated liquid phase enters a primary phase separator to be separated to obtain an organic phase and a water phase, the organic phase enters a distillation kettle to recover the solvent, the obtained 5-hydroxymethylfurfural can enter a refining unit, the separated water phase enters a secondary separation system, the organic phase firstly enters an extractor and is extracted by the organic solvent and then enters a secondary phase separator to be separated to obtain the organic phase and the water phase, the organic phase enters the distillation kettle to recover the solvent, the obtained 5-hydroxymethylfurfural can enter the refining unit, and the water phase separated by the secondary phase separator can be recycled for use as batching water.

Therefore, in a preferred implementation method of the present invention, the technical solution of the present invention includes:

a. after the cellulose biomass raw material is crushed, stirring acid by using an acid stirring screw feeder to mix the cellulose biomass raw material with an acid catalyst, feeding the mixture into a continuous screw pressure feeding device, and feeding the mixture into a furfural continuous hydrolysis kettle through a channel connected with the furfural continuous hydrolysis kettle by using a feeding device;

b. the raw material falls into the hydrolysis kettle from the upper part of the hydrolysis kettle in a gravity mode, steam is introduced into the bottom of the hydrolysis kettle, and furfural obtained after continuously generated furfural-containing steam is subjected to heat exchange by a cooler enters a refining unit; discharging the reacted furfural residue through an automatic residue discharge device arranged at the bottom of the hydrolysis kettle and feeding the furfural residue into a screw conveyor;

c. continuously adding a catalyst solution from a catalyst solution tank in the continuous conveying process of the furfural residues, mixing and conveying the catalyst solution and the organic solvent to a 5-hydroxymethylfurfural stock tank, simultaneously pumping the furfural residue-containing liquid and the organic solvent into a 5-hydroxymethylfurfural continuous hydrolysis reactor according to a certain flow ratio, introducing steam into the bottom of the reactor, and allowing the effluent reaction liquid to enter a primary separation system;

d. cooling the reaction liquid by a cooler, carrying out solid-liquid separation by a solid-liquid separator, drying the separated solid slag to be used as boiler fuel, separating the separated liquid phase in a primary phase separator to obtain an organic phase and a water phase, feeding the organic phase into a distillation kettle to recover the solvent, feeding the obtained 5-hydroxymethylfurfural into a refining unit, feeding the separated water phase into a secondary separation system, feeding the separated water phase into an extractor firstly, extracting by the organic solvent, feeding the organic phase into a secondary phase separator to separate to obtain the organic phase and the water phase, feeding the organic phase into the distillation kettle to recover the solvent, feeding the obtained 5-hydroxymethylfurfural into the refining unit, and recycling the water phase separated by the secondary phase separator to be used as batching water.

In a preferred embodiment, the cellulosic biomass feedstock can include one or a combination of two or more of the roots, stems, leaves, or fruits of various plants, such as trees, shrubs, bamboo, corn cobs, crop straw, bagasse, wood chips, fruit shells, paper waste, switchgrass, grasses; preferably, the cellulosic biomass feedstock may comprise one or a combination of two or more of corn stover, corn cobs, wheat straw, cotton stalks, sorghum stalks, bagasse, cotton seed hulls, and peanut hulls.

In a preferred embodiment, the acid catalyst is selected from one or a combination of two or more of sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, solid acids, and is preferably sulfuric acid. The acid-mixed raw material contains 1 to 10% of the acid, preferably 1%, 2%, 3%, 5%, 6%, 7%, 8%, 9% or 10% of the acid, and more preferably 2 to 5% of the acid.

In a preferred embodiment, the ratio of height to diameter of the furfural continuous hydrolysis kettle is 5-10. Preferably, it is 5.

In a preferred embodiment, the reaction temperature in the furfural continuous hydrolysis kettle is maintained at 120-250 ℃, the reaction pressure is maintained at 0.1-3.0 MPa, and the retention time is 0.5-12.0 h. Preferably, the reaction temperature in the hydrolysis kettle is maintained at 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃, 220 ℃ or 250 ℃, the reaction pressure is maintained at 0.1MPa, 0.2MPa, 0.4MPa, 0.6MPa, 0.8MPa, 1.0MPa, 1.5MPa, 2.0MPa, 2.5MPa or 3.0MPa, and the retention time is 0.5h, 1.0h, 1.5h, 2.0h, 2.5h, 3.0h, 4.0h, 5.0h, 6.0h, 7.0h, 8.0h, 9.0h, 10.0h, 11.0h or 12.0h. In one embodiment, the reaction temperature in the hydrolysis kettle is maintained at 140-200 ℃, the reaction pressure is maintained at 0.1-1.5 MPa, and the retention time is 1.0-4.0 h.

In a preferred embodiment, the furfural-containing vapor is subjected to heat exchange with the catalyst solution from the catalyst solution tank in a cooler.

In a preferred embodiment, the catalyst solution is an aqueous solution containing a metal salt, wherein the metal salt comprises one or a mixture of two or more of chloride, sulfate, phosphate, bisulfate, dihydrogen phosphate and dihydrogen phosphate of metals in any proportion, and preferably the metal salt comprises one or a mixture of two or more of aluminum chloride, ferric chloride, aluminum sulfate, ferric sulfate, sodium bisulfate, potassium bisulfate, disodium hydrogen phosphate and dipotassium hydrogen phosphate in any proportion. The mass ratio of the metal salt to the solid furfural slag is 0.05 to 0.5, and preferably, the mass ratio can be 0.05.

In a preferred embodiment, the mass concentration of the furfural residue in the mixture of furfural residue and catalyst solution is 1 to 10%, preferably 1%, 2%, 3%, 5%, 6%, 7%, 8%, 9% or 10%.

In a preferred embodiment, the organic solvent is a water-immiscible organic solvent, preferably, it is a mixture of one or more than two of methyl isobutyl ketone, methyl tetrahydrofuran, dioxane, dimethyl carbonate and n-butanol in any proportion; more preferably, it is selected from a mixed solution of methyl isobutyl ketone and n-butanol. In a preferred embodiment, the volume ratio of methyl isobutyl ketone to n-butanol is 1 to 10, preferably 1 to 10, and more preferably 1. According to the invention, when the organic solvent selects the mixed solution of methyl isobutyl ketone and n-butyl alcohol in a specific proportion, the oriented hydrolysis of cellulose in the furfural residue can be further promoted, and the content of 5-hydroxymethylfurfural in an organic phase is increased, so that the yield of 5-hydroxymethylfurfural is higher.

In a preferred embodiment, the volume flow ratio of the organic solvent to the furfural-containing residue liquid is 1 to 10, and is preferably 1.

In a preferred embodiment, the continuous 5-hydroxymethylfurfural hydrolysis reactor is a tubular reactor, and the ratio of height to diameter is 20 to 30, and is preferably 20.

In a preferred embodiment, the reaction temperature in the continuous hydrolysis reactor for 5-hydroxymethylfurfural is maintained at 140-240 ℃, the reaction pressure is maintained at 0.2-3.8 MPa, and the retention time is 0.1-5.0 h. Preferably, the reaction temperature is maintained at 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃, 220 ℃ or 240 ℃, the reaction pressure is 0.2MPa, 0.4MPa, 0.6MPa, 0.8MPa, 1.0MPa, 1.5MPa, 2.0MPa, 2.5MPa, 3.0MPa, 3.5MPa or 3.8MPa, and the residence time is 0.1h, 0.5h, 1.0h, 1.5h, 2.0h, 3.0h, 4.0h or 5.0h. In one embodiment, the reaction temperature in the 5-hydroxymethylfurfural continuous hydrolysis reactor is maintained at 150-210 ℃, the reaction pressure is maintained at 0.3-1.8 MPa, and the retention time is 0.5-2.0 h.

In a preferred embodiment, the first-stage separation system mainly comprises a solid-liquid separator, a first-stage phase separator, a distillation kettle and the like. The liquid phase outlet of the solid-liquid separator is connected with the pipeline of the first-stage phase separator, and the upper part of the phase separator is communicated with the distillation kettle.

Preferably, the solid-liquid separator is a continuous solid-liquid separator, and the separated solid can be used as boiler fuel after being dried.

Preferably, the distillation kettle is a vacuum distillation device and is connected with a condenser. The distilled organic solvent is condensed and returned to the organic solvent tank, and part of the distilled organic solvent flows into the extractor to be used as the extracting agent.

In a preferred embodiment, the two-stage separation system consists essentially of an extractor, a two-stage phase separator, and a still. The extractor is connected with the lower part of the first-stage separator, the outlet at the lower part of the extractor is communicated with the second-stage separator, and the upper part of the separator is communicated with the distillation still.

The extractor can be a batch extractor or a continuous extractor, and the volume ratio of the extracting agent to the solution to be extracted is 1-5, preferably 1.

Preferably, the ratio of the height to the diameter of the primary and secondary phase separators is 8 to 15, and preferably 8; a conical bottom may be used to facilitate discharge.

In a second aspect of the invention, the invention provides a system for continuous production of furfural and 5-hydroxymethylfurfural from cellulosic biomass, comprising: a furfural continuous hydrolysis unit, a 5-hydroxymethylfurfural continuous hydrolysis unit and a 5-hydroxymethylfurfural extraction unit; preferably, the method also comprises a furfural refining unit and a 5-hydroxymethyl furfural refining unit.

In one embodiment, the furfural continuous hydrolysis unit mixes the crushed cellulosic biomass raw material with an acid catalyst, and then adds the mixture into a furfural continuous hydrolysis kettle; the raw material falls into the hydrolysis kettle from the upper part of the hydrolysis kettle in a gravity mode, steam is introduced into the bottom of the hydrolysis kettle, furfural-containing steam generated continuously is discharged from the top of the hydrolysis kettle, and furfural is obtained after cooling; and discharging the furfural residue after reaction from the bottom of the hydrolysis kettle.

Preferably, the furfural continuous hydrolysis unit comprises an acid-mixing screw feeder, and the cellulosic biomass raw material and the acid catalyst are mixed by the acid-mixing screw feeder.

Preferably, the furfural continuous hydrolysis unit comprises a feeding device, and the mixed raw materials are added into the furfural continuous hydrolysis kettle through a channel connected with the furfural continuous hydrolysis kettle through the feeding device. In one embodiment, the feeding device forms a material plug at the discharge hole to compress the material, and the compressed material enters the furfural continuous hydrolysis kettle through a material stirring blowout preventer at the top feed hole of the furfural continuous hydrolysis kettle.

Preferably, the furfural continuous hydrolysis unit comprises a cooler and a furfural extraction unit, and furfural-containing steam discharged from the furfural continuous hydrolysis kettle is subjected to heat exchange by the cooler and then enters the furfural extraction unit for refining. In one embodiment, the cooler exchanges heat between the furfural-containing vapor and the catalyst solution exiting the catalyst solution tank.

In one embodiment, the 5-hydroxymethylfurfural continuous hydrolysis unit mixes furfural residues discharged from a furfural continuous hydrolysis kettle with a catalyst solution, then the mixture is pumped into a 5-hydroxymethylfurfural continuous hydrolysis reactor together with an organic solvent, steam is introduced into the bottom of the reactor, and the effluent reaction liquid enters the 5-hydroxymethylfurfural extraction unit.

Preferably, the reacted furfural residue enters a screw conveyor through an automatic residue discharge device arranged at the bottom of the hydrolysis kettle, and a catalyst solution from a catalyst solution tank is added in the continuous conveying process. In one embodiment, the furfural residue and the catalyst solution are mixed together and transported to a 5-hydroxymethylfurfural holding tank.

In one embodiment, the 5-hydroxymethylfurfural extraction unit enables the effluent reaction liquid to be subjected to solid-liquid separation through a solid-liquid separator, the separated liquid phase is subjected to phase separation to obtain an organic phase and an aqueous phase, the organic phase recovers the solvent to obtain 5-hydroxymethylfurfural, and the aqueous phase is extracted through the organic solvent to further recover 5-hydroxymethylfurfural.

Preferably, the reaction liquid flowing out of the 5-hydroxymethylfurfural continuous hydrolysis reactor is cooled by a cooler and then subjected to solid-liquid separation in a solid-liquid separator.

Preferably, the phase separation of the separated liquid phase is carried out in a first phase separator.

Preferably, the organic phase recovery solution is carried out in an evaporator.

Preferably, the aqueous phase extraction is carried out in an extractor.

Preferably, the extract enters a secondary phase separator for phase separation to obtain an organic phase and a water phase, and the organic phase enters a distillation kettle for solvent recovery to obtain the 5-hydroxymethylfurfural.

Preferably, the 5-hydroxymethylfurfural obtained in the still may be refined in a 5-hydroxymethylfurfural refining unit.

In one embodiment, the furfural continuous hydrolysis unit comprises: a continuous screw pressure feeding device 1, a furfural continuous hydrolysis kettle 2 and a continuous screw conveyor 3. The inlet of the furfural continuous hydrolysis kettle 2 is communicated with the continuous spiral pressure feeding device 1, the outlet of the furfural continuous hydrolysis kettle is communicated with the continuous spiral conveyor 3, and the top of the furfural continuous hydrolysis kettle 2 is provided with an aldehyde steam outlet which is connected with a cooler 4.

In one embodiment, the 5-hydroxymethylfurfural continuous hydrolysis unit comprises: a catalyst solution tank 5, a 5-hydroxymethylfurfural stock tank 7, an organic solvent tank 8 and a 5-hydroxymethylfurfural continuous hydrolysis reactor 11; in addition, a catalyst solution pump 6, an organic solvent pump 9, and a furfural residue liquid pump 10 may be further included. The catalyst solution tank 5 is communicated with the continuous screw conveyor 3, the outlet of the continuous screw conveyor 3 is communicated with the material preparation tank 7, and the material preparation tank 7 and the organic solvent tank 8 are communicated with the inlet of the 5-hydroxymethylfurfural continuous hydrolysis reactor 11.

In one embodiment, the 5-hydroxymethylfurfural extraction unit comprises: a solid-liquid separator 13, a first-stage phase separation 15 and a distillation kettle 19; preferably also comprises an extractor 14, a secondary phase separator 17; further, a cooler 12, an extract pump 16, and a condenser 18 may be included. Wherein, the inlet of the solid-liquid separator 13 is communicated with the outlet of the 5-hydroxymethylfurfural continuous hydrolysis reactor 11, the liquid phase outlet of the solid-liquid separator 13 is communicated with the first-stage phase separator 15, the upper outlet of the first-stage phase separator 15 is communicated with the distillation still 19, the lower outlet of the first-stage phase separator 15 is communicated with the extractor 14, the lower outlet of the extractor 14 is communicated with the second-stage phase separator 17, the upper outlet of the second-stage phase separator 17 is communicated with the distillation still 19, and the steam outlet of the distillation still 19 is communicated with the condenser 18.

In a preferred embodiment of the present invention, the method for continuously preparing furfural and 5-hydroxymethylfurfural from cellulosic biomass provided by the present invention is preferably as follows:

a. after the cellulosic biomass raw material is crushed, stirring acid by using an acid-stirring screw feeder to mix the cellulosic biomass raw material with an acid catalyst, feeding the mixture into a continuous screw pressure feeding device 1, and feeding the mixture into a furfural continuous hydrolysis kettle 2 through a channel connected with the furfural continuous hydrolysis kettle 2 by using a feeding device;

b. the raw material falls into the reactor from the upper part in a gravity mode, steam is introduced into the bottom part, continuously generated aldehyde-containing steam exchanges heat with the catalyst solution flowing out of the catalyst solution tank 5 through the cooler 4, and then enters the extraction unit for refining; the reacted furfural residue enters a screw conveyor 3 through an automatic residue discharge device arranged at the bottom of the hydrolysis kettle;

c. continuously adding a catalyst solution from a catalyst solution tank 5 in the continuous conveying process of the furfural residues, and conveying the furfural residues to a 5-hydroxymethylfurfural material preparing tank 7; continuously and simultaneously pumping the organic solvent in the organic solvent tank 8 and the furfural residue-containing liquid in the 5-hydroxymethylfurfural stock tank 7 into a 5-hydroxymethylfurfural continuous hydrolysis reactor 11 according to a certain flow ratio; introducing steam into the bottom of the reactor, and allowing reaction liquid continuously flowing out of the 5-hydroxymethylfurfural reactor 11 to enter a primary separation system;

d. after the reaction liquid is cooled by a cooler 12, the reaction liquid is subjected to solid-liquid separation by a solid-liquid separator 13, the separated liquid enters a primary phase separator 15, and an organic phase of the primary phase separator 15 enters a distillation kettle 19 to recover the organic solvent, so that the 5-hydroxymethylfurfural is obtained.

Preferably, the method further comprises:

e. the water phase of the first-stage phase separator 15 enters an extractor 14 to be extracted by an organic solvent, the extract liquid enters a second-stage phase separator 17, and the organic phase of the second-stage phase separator 17 enters a distillation kettle 19 to recover the solvent to obtain 5-hydroxymethylfurfural; the aqueous phase of the secondary phase separator 17 is recycled for use as dosing water.

Preferably, the organic solvent distilled in the distillation kettle 19 is condensed by the condenser 18 and then returns to the organic solvent tank 8, part of the organic solvent can directly flow into the extractor 14 to be used as an extracting agent, and the 5-hydroxymethylfurfural obtained from the distillation kettle 19 enters a refining unit for refining.

In the present invention, the various materials, apparatus, process parameters, etc. of the systems and methods are as described herein.

In a preferred embodiment, the ratio of height to diameter of the furfural continuous hydrolysis kettle 2 is 5-10. Preferably, it is 5.

In a preferred embodiment, the 5-hydroxymethylfurfural continuous hydrolysis reactor 11 is a tubular reactor, and has a height-diameter ratio of 20 to 30, preferably from 20.

In a preferred embodiment, the solid-liquid separator 13 is a continuous solid-liquid separation device.

In a preferred embodiment, the distillation still 19 is a vacuum distillation apparatus.

In a preferred embodiment, the extractor comprises a batch extractor and a continuous extractor.

In a preferred embodiment, the ratio of the height to the diameter of the first-stage phase separator 15 to the diameter of the second-stage phase separator 17 is 8 to 15, and preferably 8; a conical bottom may be used to facilitate discharge.

The invention has the following beneficial effects:

the invention takes cellulose biomass as raw material to continuously prepare furfural and 5-hydroxymethyl furfural, and realizes the preparation of two high-value chemicals through a continuous hydrolysis system, wherein, hemicellulose component is converted into furfural, cellulose component is converted into 5-hydroxymethyl furfural, and lignin can be by-produced, thus improving the utilization rate of the raw material components to the maximum extent. In the furfural preparation process, the continuous stripping is favorable for improving the production efficiency and yield of furfural, and meanwhile, the sulfuric acid contained in furfural residues can be continuously used as a partial catalyst for the hydrolysis preparation of 5-hydroxymethylfurfural, so that the use of subsequent sulfuric acid is avoided. In the preparation process of 5-hydroxymethylfurfural, a composite catalytic system with L acid and B acid is formed by utilizing the residual sulfuric acid of furfural residues and metal salt, so that the preparation of 5-hydroxymethylfurfural by hydrolyzing raw materials is promoted, and the problem of equipment corrosion caused by acid is effectively solved. In addition, the two-phase hydrolysis in the continuous tubular reactor is adopted, so that the oriented hydrolysis of the cellulose in the furfural residue is further promoted. The organic solvent used in the two-phase hydrolysis has the characteristics of insolubility in water and low boiling point, the selection of the specific organic mixed solvent improves the efficiency of product phase separation and promotes the reaction, and meanwhile, the organic solvent is easy to recycle and has the characteristics of low energy consumption and less three-waste discharge. Particularly, the whole hydrolysis process realizes continuity, and the cellulose biomass can be continuously and synchronously prepared into furfural and 5-hydroxymethyl furfural high-value chemicals.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention.

Wherein the reference numerals denote: the device comprises a continuous spiral pressure feeding device 1, a furfural continuous hydrolysis kettle 2, a continuous spiral conveyor 3, a cooler 4, a catalyst solution tank 5, a catalyst solution pump 6, a 75-hydroxymethylfurfural stock tank, an organic solvent tank 8, an organic solvent pump 9, a furfural residue liquid pump 10, a continuous hydroxymethylfurfural hydrolysis reactor 115, a cooler 12, a solid-liquid separator 13, an extractor 14, a first-stage phase separator 15, an extraction liquid pump 16, a second-stage phase separator 17, a condenser 18 and a distillation kettle 19.

Detailed Description

The present invention is described in more detail below to facilitate an understanding of the present invention.

It should be understood that the terms or words used in the specification and claims should not be construed as having meanings defined in dictionaries, but should be interpreted as having meanings that are consistent with their meanings in the context of the present invention on the basis of the following principles: the concept of terms may be defined appropriately by the inventor for the best explanation of the invention.

The experimental procedures in the following examples are all conventional ones unless otherwise specified. The examples do not specify particular techniques or conditions, and are to be construed in accordance with the description of the art in the literature or with the specification of the product.

Furfural yield% = furfural mass in furfural-containing vapor/biomass raw material mass × 100%

Yield of 5-hydroxymethylfurfural% = mass of 5-hydroxymethylfurfural in reaction liquid/mass of biomass raw material × 100%

Example 1

The concentration of sulfuric acid after straw crushing and acid mixing is 5%, the mixture is continuously added into a furfural hydrolysis kettle for reaction, the reaction temperature is 150 ℃, the pressure is 0.4MPa, the reaction residence time is 2 hours, and the mass yield of furfural is 8.6%. The mass ratio of the aluminum chloride to the furfural residues is 0.4. The volume ratio of methyl isobutyl ketone to n-butanol in the organic solvent is 6. The two are continuously pumped into a 5-hydroxymethylfurfural continuous hydrolysis tubular reactor at the same time for reaction, the reaction temperature is 180 ℃, the pressure is 1.0MPa, the retention time is 0.6h, and the mass yield of the 5-hydroxymethylfurfural is 7.3%.

Example 2

The concentration of sulfuric acid after the corncobs are crushed and mixed with acid is 2.5 percent, the corncobs are continuously added into a furfural hydrolysis kettle for reaction, the reaction temperature is 170 ℃, the pressure is 0.7MPa, the reaction residence time is 2 hours, and the mass yield of furfural is 8.8 percent. The mass ratio of the aluminum sulfate to the furfural residues is 0.1. The volume ratio of methyl isobutyl ketone to n-butanol in the organic solvent is 8: 1. the two are continuously pumped into a 5-hydroxymethylfurfural continuous hydrolysis tubular reactor at the same time for reaction, the reaction temperature is 190 ℃, the pressure is 1.2MPa, the retention time is 0.8h, and the mass yield of the 5-hydroxymethylfurfural is 7.5 percent.

Example 3

The concentration of sulfuric acid after crushing and acid mixing of equivalent straws and corncobs is 4.5%, the mixture is continuously added into a furfural hydrolysis kettle for reaction, the reaction temperature is 180 ℃, the pressure is 1.0MPa, the reaction residence time is 2 hours, and the mass yield of furfural is 9.0%. The equivalent aluminum chloride and ferric chloride are mixed, the mass ratio of the mixed salt to the furfural residue is 0.3. The volume ratio of methyl isobutyl ketone to n-butyl alcohol in the organic solvent is 3:1. the two are simultaneously and continuously pumped into a 5-hydroxymethylfurfural continuous hydrolysis tubular reactor for reaction, the reaction temperature is 150 ℃, the pressure is 0.4MPa, the retention time is 1h, and the mass yield of the 5-hydroxymethylfurfural is 7.1 percent.

Example 4

The concentration of sulfuric acid after the corncobs are crushed and mixed with acid is 5%, the corncobs are continuously added into a furfural hydrolysis kettle for reaction, the reaction temperature is 140 ℃, the pressure is 0.2MPa, the reaction residence time is 2 hours, and the mass yield of furfural is 8.3%. The mass ratio of the sodium bisulfate to the furfural residues is 0.05. The volume ratio of methyl isobutyl ketone to n-butanol in the organic solvent is 1. The two are simultaneously and continuously pumped into a 5-hydroxymethylfurfural continuous hydrolysis tubular reactor for reaction, the reaction temperature is 200 ℃, the pressure is 1.4MPa, the retention time is 1h, and the mass yield of the 5-hydroxymethylfurfural is 6.8 percent.

Example 5

The concentration of sulfuric acid after crushing the corncobs and mixing with acid is 2%, the sulfuric acid is continuously added into a furfural hydrolysis kettle for reaction, the reaction temperature is 200 ℃, the pressure is 1.4MPa, the reaction residence time is 2 hours, and the mass yield of furfural is 9.2%. The mass ratio of the dipotassium hydrogen phosphate to the furfural residues is 0.25 to 1, and the concentration of the furfural residues is 8%. The volume ratio of methyl isobutyl ketone to n-butanol in the organic solvent is 6. The two are simultaneously and continuously pumped into a 5-hydroxymethylfurfural continuous hydrolysis tubular reactor for reaction, the reaction temperature is 160 ℃, the pressure is 0.5MPa, the retention time is 1h, and the mass yield of the 5-hydroxymethylfurfural is 6.6%.

Example 6

The concentration of sulfuric acid after crushing and acid mixing of equivalent straw and corncob is 3.5%, the mixture is continuously added into a furfural hydrolysis kettle for reaction, the reaction temperature is 165 ℃, the pressure is 0.6MPa, the reaction residence time is 2 hours, and the mass yield of furfural is 9.1%. Equal mass of dipotassium phosphate and disodium phosphate are mixed, the mass ratio of the mixed salt to the furfural residues is 0.15. The volume ratio of methyl isobutyl ketone to n-butanol in the organic solvent is 8. The two are simultaneously and continuously pumped into a 5-hydroxymethylfurfural continuous hydrolysis tubular reactor for reaction, the reaction temperature is 170 ℃, the pressure is 0.7MPa, the retention time is 1h, and the mass yield of the 5-hydroxymethylfurfural is 6.2 percent.

Comparative example 1

The concentration of sulfuric acid after crushing the corncobs and mixing with acid is 2.5%, the corncobs are continuously added into a furfural hydrolysis kettle for reaction, the reaction temperature is 170 ℃, the pressure is 0.7MPa, the reaction residence time is 2 hours, and the mass yield of furfural is 8.8%. The mass ratio of the aluminum sulfate to the furfural residues is 0.1. The volume flow ratio of the organic solvent methyl isobutyl ketone to the furfural-containing residue liquid is 5. The two are continuously pumped into a 5-hydroxymethylfurfural continuous hydrolysis tubular reactor at the same time for reaction, the reaction temperature is 190 ℃, the pressure is 1.2MPa, the retention time is 0.8h, and the mass yield of the 5-hydroxymethylfurfural is 4.9 percent.

Comparative example 2

The concentration of sulfuric acid after the corncobs are crushed and mixed with acid is 5%, the corncobs are continuously added into a furfural hydrolysis kettle for reaction, the reaction temperature is 140 ℃, the pressure is 0.2MPa, the reaction residence time is 2 hours, and the mass yield of furfural is 8.3%. The mass ratio of the sodium bisulfate to the furfural residues is 0.05. The volume flow ratio of the organic solvent n-butanol to the furfural residue-containing liquid is 1. The two are simultaneously and continuously pumped into a 5-hydroxymethylfurfural continuous hydrolysis tubular reactor for reaction, the reaction temperature is 200 ℃, the pressure is 1.4MPa, the retention time is 1h, and the mass yield of the 5-hydroxymethylfurfural is 4.3 percent.

The above are only some preferred embodiments of the present invention, but the scope of the present invention is not limited thereto, and the present invention is not limited by the sequence of the embodiments, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention should be covered by the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for continuously preparing furfural and 5-hydroxymethylfurfural from cellulose biomass comprises the following steps:

b. the raw material falls into the hydrolysis kettle from the upper part of the hydrolysis kettle in a gravity mode, steam is introduced into the bottom of the hydrolysis kettle, furfural-containing steam generated continuously is discharged from the top of the hydrolysis kettle, and furfural is obtained after cooling; discharging furfural residues after reaction from the bottom of the hydrolysis kettle;

2. The method of claim 1 wherein the cellulosic biomass feedstock is mixed with the acid catalyst by an acid-mixing screw feeder.

3. The method according to claim 1 or 2, wherein the mixed raw material of the cellulose biomass raw material and the acid catalyst is fed into the furfural continuous hydrolysis kettle through a channel of a feeding device connected with the furfural continuous hydrolysis kettle, wherein the feeding device can be a continuous screw pressure feeding device; preferably, the feeding device forms a material plug at a discharge hole to compress the material, and the compressed material enters the furfural continuous hydrolysis kettle through a material stirring blowout preventer at a feed hole at the top of the furfural continuous hydrolysis kettle.

4. The method according to any one of claims 1 to 3, wherein the furfural-containing steam is subjected to heat exchange by a cooler and then enters an extraction unit for refining.

5. The method according to any one of claims 1 to 4, wherein the reacted furfural residue is discharged through an automatic residue discharge device arranged at the bottom of the hydrolysis kettle and enters a screw conveyor, and the catalyst solution is continuously added from a catalyst solution tank during the continuous conveying of the furfural residue.

6. The method according to any one of claims 1 to 5, wherein the reaction solution flowing out of the continuous hydrolysis reactor for 5-hydroxymethylfurfural is cooled by a cooler and then subjected to solid-liquid separation in a solid-liquid separator.

7. The process according to any one of claims 1 to 6, wherein the aqueous phase obtained by phase separation is subjected to organic solvent extraction to further recover 5-hydroxymethylfurfural.

8. The method according to any one of claims 1 to 7, wherein the aqueous phase obtained by phase separation is extracted by an organic solvent, and is subjected to phase separation to obtain an organic phase and an aqueous phase, and the organic phase is subjected to solvent recovery to obtain 5-hydroxymethylfurfural; the aqueous phase can be recycled for use as feed water.

9. The method according to any one of claims 1 to 8, wherein the 5-hydroxymethylfurfural obtained after recovering the solvent is fed to a refining unit for refining.

10. The method according to any one of claims 1 to 9, wherein the reaction liquid flowing out of the continuous 5-hydroxymethylfurfural hydrolysis reactor enters a primary separation system, is cooled by a cooler and is subjected to solid-liquid separation by a solid-liquid separator, the separated liquid phase enters a primary phase separator and is separated to obtain an organic phase and a water phase, and the organic phase enters a distillation kettle to recover the solvent to obtain 5-hydroxymethylfurfural; the separated water phase enters a secondary separation system, firstly enters an extractor, is extracted by an organic solvent and then enters a secondary phase separator for separation to obtain an organic phase and a water phase, and the organic phase enters a distillation kettle for recovering the solvent to obtain 5-hydroxymethylfurfural; the aqueous phase separated in the secondary phase separator can be recycled for use as feed water.

11. The method according to any one of claims 1 to 10, characterized in that it comprises:

a. after the cellulose biomass raw material is crushed, stirring acid by using an acid-stirring screw feeder to mix the cellulose biomass raw material with an acid catalyst, feeding the mixture into a continuous screw pressure feeding device, and feeding the mixture into a furfural continuous hydrolysis kettle through a channel connected with the furfural continuous hydrolysis kettle by using a feeding device;

c. continuously adding a catalyst solution from a catalyst solution tank in the continuous conveying process of the furfural residues, mixing and conveying the furfural residues and the organic solvent to a 5-hydroxymethylfurfural stock tank, simultaneously pumping the furfural residue-containing liquid and the organic solvent into a 5-hydroxymethylfurfural continuous hydrolysis reactor according to a certain flow ratio, introducing steam into the bottom of the reactor, and allowing the effluent reaction liquid to enter a primary separation system;

d. cooling the reaction liquid by a cooler, carrying out solid-liquid separation by a solid-liquid separator, allowing the separated liquid phase to enter a first-stage phase separator for separation to obtain an organic phase and a water phase, allowing the organic phase to enter a distillation kettle for solvent recovery, allowing the obtained 5-hydroxymethylfurfural to enter a refining unit, allowing the separated water phase to enter a second-stage separation system, allowing the water phase to enter an extractor, extracting by the organic solvent, allowing the water phase to enter a second-stage phase separator for separation to obtain the organic phase and the water phase, allowing the organic phase to enter the distillation kettle for solvent recovery, and allowing the obtained 5-hydroxymethylfurfural to enter the refining unit.

12. The method of any of claims 1-11, wherein the cellulosic biomass feedstock comprises roots, stems, leaves, or fruits of various plants, such as one or a combination of two or more of trees, shrubs, bamboo, corn cobs, crop straw, sugar cane bagasse, wood chips, fruit shells, paper waste, switchgrass, grasses; preferably, the cellulosic biomass feedstock may include one or a combination of two or more of corn stover, corn cobs, wheat straw, cotton stalk, sorghum stalk, bagasse, cotton seed hulls, and peanut hulls.

13. The process according to any one of claims 1 to 12, wherein the acid catalyst is selected from one or a combination of two or more of sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, solid acids, and preferably sulfuric acid; the acid-mixed raw material contains 1 to 10% of the acid, preferably 2 to 5% of the acid.

14. The method according to any one of claims 1 to 13, wherein the ratio of height to diameter of the furfural continuous hydrolysis kettle is 5 to 10.

15. The method according to any one of claims 1 to 14, wherein the reaction temperature in the furfural continuous hydrolysis kettle is maintained at 120 to 250 ℃, the reaction pressure is maintained at 0.1 to 3.0MPa, and the residence time is 0.5 to 12.0h; preferably, the reaction temperature in the hydrolysis kettle is maintained at 140-200 ℃, the reaction pressure is maintained at 0.1-1.5 MPa, and the retention time is 1.0-4.0 h.

16. The process according to any one of claims 1 to 15, wherein the furfural-containing steam is subjected to heat exchange with the catalyst solution from the catalyst solution tank in a cooler.

17. The method as claimed in any one of claims 1 to 16, wherein the catalyst solution is an aqueous solution containing a metal salt, the metal salt comprising one or a mixture of two or more of chloride, sulfate, phosphate, hydrogen sulfate, dihydrogen phosphate and dihydrogen phosphate of the metal in any ratio; preferably, the metal salt comprises one or a mixture of more than two of aluminum chloride, ferric chloride, aluminum sulfate, ferric sulfate, sodium bisulfate, potassium bisulfate, disodium hydrogen phosphate and dipotassium hydrogen phosphate in any proportion; the mass ratio of the metal salt dosage to the solid furfural residue is 0.05-0.5.

18. The method according to any one of claims 1 to 17, wherein the mass concentration of the furfural residue in the mixture of the furfural residue and the catalyst solution is 1 to 10%.

19. The method according to any one of claims 1 to 18, wherein the organic solvent is a water-immiscible organic solvent, preferably one or a mixture of two or more selected from the group consisting of methyl isobutyl ketone, methyl tetrahydrofuran, dioxane, dimethyl carbonate, and n-butanol at any ratio.

20. The method according to claim 19, wherein the organic solvent is selected from a mixture of methyl isobutyl ketone and n-butanol, and the volume ratio of methyl isobutyl ketone to n-butanol is 1-10.

21. The method according to any one of claims 1 to 20, wherein the volume flow ratio of the organic solvent to the furfural residue-containing liquid is 1 to 10.

22. The method according to any one of claims 1 to 21, wherein the continuous hydrolysis reactor for 5-hydroxymethylfurfural is a tubular reactor, and the height-diameter ratio is 20-30.

23. The method according to any one of claims 1 to 22, wherein the reaction temperature in the continuous hydrolysis reactor for 5-hydroxymethylfurfural is maintained at 140 to 240 ℃, the reaction pressure is maintained at 0.2 to 3.8MPa, and the retention time is 0.1 to 2.0 hours; preferably, the reaction temperature is maintained between 150 and 210 ℃, the reaction pressure is maintained between 0.3 and 1.8MPa, and the retention time is 0.5 to 1.0h.

24. The process according to any one of claims 1 to 23, wherein the solid-liquid separator is a continuous solid-liquid separator, and the separated solids are dried and used as boiler fuel.

25. The method of any one of claims 1 to 24, wherein the method comprises:

a. after the cellulose biomass raw material is crushed, stirring acid by using an acid-stirring screw feeder to mix the cellulose biomass raw material with an acid catalyst, feeding the mixture into a continuous screw pressure feeding device (1), and feeding the mixture into a furfural continuous hydrolysis kettle (2) through a channel connected with the furfural continuous hydrolysis kettle (2) by using a feeding device;

b. the raw materials fall from the upper part in a gravity mode, steam is introduced into the bottom part, continuously generated aldehyde-containing steam exchanges heat with the catalyst solution flowing out of the catalyst solution tank (5) through the cooler (4), and then the aldehyde-containing steam enters the extraction unit for refining; the reacted furfural residue enters a screw conveyor (3) through an automatic residue discharge device arranged at the bottom of the hydrolysis kettle;

c. continuously adding a catalyst solution from a catalyst solution tank (5) in the continuous conveying process of the furfural residues, and conveying the furfural residues to a 5-hydroxymethylfurfural standby tank (7); continuously and simultaneously pumping an organic solvent in an organic solvent tank (8) and a furfural residue-containing liquid in a 5-hydroxymethylfurfural standby tank (7) into a 5-hydroxymethylfurfural continuous hydrolysis reactor (11) according to a certain flow ratio; introducing steam into the bottom of the reactor, and allowing reaction liquid continuously flowing out of the 5-hydroxymethylfurfural reactor (11) to enter a primary separation system;

d. after the reaction liquid is cooled by a cooler (12), solid-liquid separation is carried out by a solid-liquid separator (13), the separated liquid enters a first-stage phase separator (15), the organic phase of the first-stage phase separator (15) enters a distillation kettle (19) to recover the organic solvent, and the 5-hydroxymethylfurfural is obtained.

26. The method of claim 25, further comprising:

e. the water phase of the first-stage phase separator (15) enters an extractor (14) to be extracted by an organic solvent, the extract liquid enters a second-stage phase separator (17), and the organic phase of the second-stage phase separator (17) enters a distillation kettle (19) to recover the solvent to obtain 5-hydroxymethylfurfural; the aqueous phase of the secondary phase separator (17) is recycled for use as dosing water.

27. The method of claim 25 or 26, further comprising: the organic solvent distilled in the distillation kettle (19) is condensed by a condenser (18) and then returns to the organic solvent tank (8), part of the organic solvent can directly flow into an extractor (14) to be used as an extracting agent, and the 5-hydroxymethylfurfural obtained from the distillation kettle (19) enters a refining unit for refining.

28. A system for continuous production of furfural and 5-hydroxymethylfurfural from cellulosic biomass, comprising: a furfural continuous hydrolysis unit, a 5-hydroxymethylfurfural continuous hydrolysis unit and a 5-hydroxymethylfurfural extraction unit; preferably, the method also comprises a furfural refining unit and a 5-hydroxymethylfurfural refining unit.

29. The system of claim 28,

the furfural continuous hydrolysis unit is used for mixing crushed cellulosic biomass raw materials with an acid catalyst and then adding the mixture into a furfural continuous hydrolysis kettle; the raw materials fall into the hydrolysis kettle from the upper part of the hydrolysis kettle in a gravity mode, steam is introduced into the bottom of the hydrolysis kettle, continuously generated furfural-containing steam is discharged from the top of the hydrolysis kettle, and furfural is obtained after cooling; discharging furfural residues after reaction from the bottom of the hydrolysis kettle;

the 5-hydroxymethylfurfural continuous hydrolysis unit mixes furfural residues discharged from a furfural continuous hydrolysis kettle with a catalyst solution, then the mixture is pumped into a 5-hydroxymethylfurfural continuous hydrolysis reactor together with an organic solvent, steam is introduced into the bottom of the reactor, and the effluent reaction liquid enters a 5-hydroxymethylfurfural extraction unit;

the 5-hydroxymethylfurfural extraction unit enables the effluent reaction liquid to be subjected to solid-liquid separation through a solid-liquid separator, the separated liquid phase is subjected to phase separation to obtain an organic phase and a water phase, the organic phase is subjected to solvent recovery to obtain 5-hydroxymethylfurfural, and the water phase is subjected to organic solvent extraction to further recover 5-hydroxymethylfurfural.

30. The system of claim 28 or 29, wherein the furfural continuous hydrolysis unit comprises an acid-mixing screw feeder, and the cellulosic biomass feedstock is mixed with the acid catalyst by the acid-mixing screw feeder.

31. The system according to any one of claims 28 to 30, wherein the furfural continuous hydrolysis unit comprises a feeding device, and the mixed raw materials are fed into the furfural continuous hydrolysis kettle through a channel connected with the furfural continuous hydrolysis kettle through the feeding device; preferably, the feeding device forms a material plug at a discharge hole to compress the material, and the compressed material enters the furfural continuous hydrolysis kettle through a material stirring blowout preventer at a feed hole at the top of the furfural continuous hydrolysis kettle.

32. The system of any one of claims 28 to 31, wherein the furfural continuous hydrolysis unit comprises a cooler and a furfural extraction unit, furfural-containing steam discharged from a furfural continuous hydrolysis kettle is subjected to heat exchange by the cooler and then enters the furfural extraction unit for refining; preferably, the cooler exchanges heat between the furfural-containing steam and the catalyst solution flowing out of the catalyst solution tank.

33. The system of any one of claims 29 to 32, wherein the reacted furfural residue is introduced into a screw conveyor through an automatic residue discharge device arranged at the bottom of the hydrolysis kettle, and the catalyst solution from the catalyst solution tank is added during continuous conveying.

34. The system according to any one of claims 29 to 33, wherein the reaction solution flowing out of the continuous 5-hydroxymethylfurfural hydrolysis reactor is cooled by a cooler and then subjected to solid-liquid separation in a solid-liquid separator.

35. The system of any one of claims 29 to 34, wherein the extract enters a secondary phase separator for phase separation to obtain an organic phase and an aqueous phase, and the organic phase enters a distillation still for solvent recovery to obtain 5-hydroxymethylfurfural.

36. The system according to any one of claims 28 to 35,

the furfural continuous hydrolysis unit comprises: a continuous screw pressure feeding device (1), a furfural continuous hydrolysis kettle (2) and a continuous screw conveyor (3); wherein the inlet of the furfural continuous hydrolysis kettle (2) is communicated with the continuous spiral pressure feeding device (1), the outlet of the furfural continuous hydrolysis kettle is communicated with the continuous spiral conveyor (3), and the top of the furfural continuous hydrolysis kettle (2) is provided with an aldehyde steam outlet which is connected with the cooler (4);

the 5-hydroxymethylfurfural continuous hydrolysis unit comprises: a catalyst solution tank (5), a 5-hydroxymethylfurfural preparation tank (7), an organic solvent tank (8) and a 5-hydroxymethylfurfural continuous hydrolysis reactor (11); in addition, the system also comprises a catalyst solution pump (6), an organic solvent pump (9) and a furfural residue liquid pump (10); the catalyst solution tank (5) is communicated with the continuous screw conveyor (3), the outlet of the continuous screw conveyor (3) is communicated with the material preparation tank (7), and the material preparation tank (7) and the organic solvent tank (8) are communicated with the inlet of the 5-hydroxymethylfurfural continuous hydrolysis reactor (11);

the 5-hydroxymethylfurfural extraction unit comprises: a solid-liquid separator (13), a first-stage phase separation (15) and a distillation kettle (19); wherein, the inlet of the solid-liquid separator (13) is communicated with the outlet of the 5-hydroxymethylfurfural continuous hydrolysis reactor (11), the liquid phase outlet of the solid-liquid separator (13) is communicated with the first-stage phase separator (15), and the upper outlet of the first-stage phase separator (15) is communicated with the distillation kettle (19).

37. The system of claim 36, wherein the 5-hydroxymethylfurfural extraction unit further comprises an extractor (14), a secondary phase separator (17), and may further comprise a cooler (12), an extract pump (16), a condenser (18); wherein, the lower outlet of the first-stage separator phase separator (15) is communicated with the extractor (14), the lower outlet of the extractor (14) is communicated with the second-stage phase separator (17), the upper outlet of the second-stage phase separator (17) is communicated with the distillation kettle (19), and the steam outlet of the distillation kettle (19) is communicated with the condenser (18).

38. The system according to claim 36 or 37, wherein the height-diameter ratio of the furfural continuous hydrolysis kettle (2) is 5-10.

39. The system according to any one of claims 36 to 38, wherein the continuous hydrolysis reactor (11) for 5-hydroxymethylfurfural is a tubular reactor with a height-diameter ratio of 20 to 30.

40. The system according to any one of claims 36 to 39, wherein the solid-liquid separator (13) is a continuous solid-liquid separation device.